A police ballistics expert has revealed how Reeva Steenkamp covered her head to protect herself in a toilet cubicle as her boyfriend Oscar Pistorius opened fire.

Captain Christian Mangena was giving evidence on day 13 of the Paralympian's murder trial, which has now been adjourned until next week.

The initial bullet was the first of four fired by the double-amputee athlete.

Capt Mangena told the court in Pretoria that Ms Steenkamp fell back onto a magazine holder in the toilet after being hit by the first bullet.

The second bullet that was fired through the wooden door missed, he said, before ricocheting off a wall and bruising her back.

Pistorius awaits the start of day 13

However, Ms Steenkamp, 29, was hit by the third and fourth bullets - in the arm and the head.

Capt Mangena said she was crossing both hands over her head to protect herself when the third and fourth bullets struck.

Video:Pistorius Trial: Day Twelve

One of those bullets went through Ms Steenkamp's left hand before penetrating her skull.

The policeman said he couldn't determine the order of the last two shots but revealed they left Ms Steenkamp slumped with her head on the toilet seat.

"She ended up with her head on top of the toilet seat, and the lower part of her body on the rack," Capt Mangena said.

The ballistics expert also concluded that Pistorius was "likely" to have been on his stumps when he fired the shots and was "firing from a distance greater than 60 centimetres" but no more than three metres.

Capt Mangena claimed the type of bullets in Pistorius' gun were designed to cause maximum damage and were often used for self-defence.

"It hits the target, it opens up, it creates six talons, and these talons are sharp," he said. "It cuts through the organs of a human being."

The victim's mother, June Steenkamp, was once again in court hearing the evidence relating to her daughter's death.

In response to Capt Mangena's evidence, defence lawyer Barry Roux argued that the state was coming up with versions to "constitute premeditated murder".

Mr Roux said the defence's own ballistics experts would challenge evidence regarding the sequence of shots.

He also revealed how defence experts recovered a bullet and fragments from the toilet bowl that police missed.

The court then heard from Colonel Ian Van Der Nest, a blood spatter expert from the Forensic Science Laboratory in Pretoria.

He said Ms Steenkamp's long hair and short pants were soaked in blood.

Col Van Der Nest told the court there was no evidence of "blunt force" inflicted by hitting or beating.

Pistorius, who won two gold medals at the Paralympics in London in 2012, is charged with premeditated murder.

He is also accused of illegally possessing ammunition, as well as two further counts related to shooting a gun in public in two separate incidents before the killing.

The athlete denies the charges and says he shot Ms Steenkamp in error after mistaking her for an intruder.

The trial has now been adjourned until Monday, when the state will begin calling its final four or five witnesses.